Reservoir Housing

posted Jan 24, 2013, 7:14 PM by Andrew Stock

Lots of good things happening right now, and I finally feel like I'm hitting a stride as far as making progress towards completion. It's all starting to come together! 

First of all, I decided I wanted to start on the repairs of my midplate. The plate came stock with a few large gaps for passing cables between the lower section (where the power supply and hard drives are supposed to be located) and the upper section (where the motherboard, etc. is located.) These holes are in a very front-and-center location though, and I think it ruins the aesthetic of the display window since they will literally be right in front of it. Also, from the previous very simple mod, I had cut two holes up towards the front for my tubing to pass through. So... I laid it out to try and figure out how I wanted to fix it:

I played with the idea of using JBWeld... but I was concerned I would just get burned again like I did with the Bondo. After all, I used a JB Weld product (the steelstick) too, and that didn't hold up either. I also considered using some of that low temperature welding stuff... but considering how well that went, I just decided to take it to the local welding shop for a consult. $100 bucks later, I decided it was well worth letting them figure it out.   I got a cut rate on the work (and there's a lot to be done - aluminum isn't easy), and in exchange they would work on it over the course of a week instead of making it a priority. Deal!  Hopefully, it should be done this coming weekend!

Once that piece comes back, I can finally build my painting booth and get started on painting! Maybe as early as this weekend? 

Anyway, in the meantime, I went on to another task: putting together the reservoir. Being that I am always cautious about firsts... I decided it was probably a good idea to try out my plan before I jumped right in. I started out with a little toy I made a while back while testing cutting and gluing acrylic:

I didn't prepare the piece especially well when I glued it together, and spent only about 30 seconds measuring it before cutting it... so things were a little rough for the purpose of holding water. I laid out a piece of 400 grit sandpaper on my work surface, clamped it down, and went to work sanding it flat. Sanding it this way made sure the surface was completely flat for gluing it later. 

Next, I took a little scrap piece left over from the radiator housing and glued the sanded triangle to it. You can kinda see the glue seams when viewing it from the inside. To get the glue placed exactly in what was a relatively small area, I used one of these:

Terrifyingly huge, no?   Worked way better than the little squeeze bottle I had before, though. The glue is so thin, it would fall right out of the needle when turned upside down, which made it impossible to control. With this plunger applicator, the suction kept the glue in place. Much cleaner!

I also made an 'extended cut' version for putting glue down into the reservoir after it was partially assembled:

Anyway, I put the whole thing together, and used that black acrylic that I tapped in my previous post as the lid. I filled it with water, threw on a g1/4 plug, set it on some paper towels, and let it sit for a few days to see if any serious leaks developed:

After a day or so, I scoped it out and noticed only a very tiny bead of water in one of the corners. Not too bad considering the little prep work I did on this. I'd say experiment passed! Time for the real thing! 

First, I had to cut my acrylic tube to the right length. I measured it all out (about six times... I was really nervous as this tube was actually fairly expensive to obtain... ) marked it, then lined the mark with some painters tape to make the cutting line extra clear. No room for mistakes!

Next, I broke out the miter saw with my finishing blade, and very slowly trimmed through layers of the tube at a time. I would make a 1" cut, turn the tube, make another, turn again, etc etc. Each time the cut would be a little deeper.

This helped make sure that I didn't heat the acrylic up so much that it melted and deformed. It also made sure the cut was that much more strait! After a few minutes of tiny cuts:

Now, I applied the same treatment with sandpaper to the bottom and top of the tube. I placed the sandpaper on a spare aluminum sheet this time, too, just to make sure the surface was perfectly flat:

Looks good!

Done with that... phew! I was nervous the whole time. It must be what it feels like to perform surgery. No room for mistakes! 

Now, I moved on to cutting and preparing the top and bottom of the reservoir. I covered the pieces in masking tape, marked up the areas with pencil, and bathed it in cutting oil to make sure I had a good clean cut:

After cutting, I tapped them using my handy tapping tool I created in my previous postings. Now I was ready to start putting the thing together when I realized... I'm obviously going to need to take the masking tape with all my measurements off before I can glue it.  But how do I make sure that the tube is glued in exactly the right place? Hmmm...  If only I had some kind of guide... or template...

Wait. I can totally make a template. 

So, I broke out the MDF board I used to make my router template for my radiator housing earlier, and traced up a quick template. 

A little handy work with the jigsaw and drum sander later:

Perfect fit! Now I can simply line the template up with the base triangle of acrylic, and the tube should be in exactly the right place for both the top and bottom triangles! 

In my design, I thought it would be really cool to put an illuminated 'prism' of acrylic in the center of the reservoir. All I had to do was cut it out of some stock acrylic, glue it to the top and bottom just like the tube, and then drill into the ends. Simple, no? So I cut out the prism from some 1" thick clear acrylic I had left over. That's when I noticed a problem:

The prism isn't strait! But why... how? 

Some research online showed an interesting property of cast acrylic that I was not aware of, called outgassing. Once exposed to air for a little while, the surfaces of the acryilc will start to vent a bit and actually shrink a tiny amount. It's not noticeable on small pieces or heavy flat pieces, but on long thin bars like this it becomes painfully apparent. That, mixed with internal stresses that are released after cutting cast acrylic, and you end up with a retarded prism.  The only way that people mentioned to fix this is through annealing... but I don't have the equipment for that. 

Anyway, I figured the bend was minor enough that I could just correct it by gluing it dead-on strait to both ends of the reservoir... which would force it to 'stand up strait'. Boy was I wrong... but we'll get to that. 

I proceeded to make a template much like the one for my tube, this time for the smaller inner prism. 

I lined it up just to make sure things looked right... also to double check the process and order for gluing. Looks good so far...

I then went on to use my flat-sanding process to prepare the prism. I ran all three sides across it for a good long while until all the imperfections were removed, giving me a nice frosted appearance which should diffuse light pretty well:

So, I clamped my template and bottom piece down and glued the prism into place. I just shot some glue where the prism needed to go (just a few drops into the center of the template), then pushed the prism in on top of it:

I thought I was good here... but the fluid dynamics I was counting on to spread the glue out evenly (capillary action) turned against me. The nearby MDF proved to be tempting enough to pull some of the glue out of the prism and under itself. I learned two things here:

1) Science never does you any favors. 

2) Apparently MDF can weld to acrylic just like another piece of acrylic. 

Long story short, the bottom was pretty badly marred by this. After a bit of careful scraping to remove the MDF bonded to the surface, I ended up with this:

Ouch. But all is not lost... for I now have a chance to practice my acrylic repair using all of that Novus stuff I bought a while back. It actually came out pretty well... barely noticeable now. Fortunately this is the underside of the top of the reservoir anyway, so you'll never be able to see it. It bothers me slightly, but not enough to warrant starting over! 

Anyway, I went on to use my template again to glue the tube in place around the prism:

The mess on the surface next to the prism is actually just polish that I failed to clean up completely. It wasn't visible at first, but as it dried it turned white. It was a pain in the but to clean (considering it was down in the middle of a giant tube) but I managed with a dowel, some paper towels, and some patience. 

Now, for another slight miscalculation, which was going to turn into a really neat feature, but which ultimately ended in complete defeat. 

The template worked great for lining up the first piece... but now, how am I supposed to use it to line up the other side of the prism now that the tube is in the way? I obviously couldn't have lined it up first, as then I would be unable to put the tube on. I designed something that ended up being impossible to build. Go figure.  

No matter! Where there is a will, there is a way, they say. And I came up with a neat idea... what if I cut out some circles that acted as a spacer between the inside of the tube and the outside of the prism? I could then put these spacers inside the reservoir at the top and bottom. This would not only ensure the prism was perfectly aligned since all the spacers would be identical, but I could use it to hide the attachment points of the prism, which weren't as perfect as I wanted. Double win, right?

I cut out a circular template from MDF, much like the other pieces. I then used it, with my router, to make a few identical acrylic circles. I then carved out a triangle in the center which the prism would fit onto.

My plan was then to cut 5mm half circle edges off of the perimeter of the circle, so that water could flow through... but... as I was fitting the first circle onto the prism (which was glued into the reservoir if you will recall)... 

Off it came!   Only the slightest bend to make the prism stand up strait, and the bottom of the prism broke off of the bottom of the reservoir.  Well... so much for that idea. I sat around and thought about it for a bit, and then decided to scrap the whole 'prism inside the reservoir' thing. It was ended up a lot more work than I had hoped, and I wasn't even completely convinced that I would be able to generate the effect I wanted. 

Besides... I already had a better idea. 

But first, I wanted to complete the reservoir "sans-prism". That was a quick task... just a shot of glue here and there... dry overnight... fill with water for testing... done!

But what's this?

A tiny, stubborn leak. There's always one! No matter, I'll just drain it and give another shot of glue in that spot... that should do it!

Anyway... back to the better idea about the prism thing I mentioned earlier... I got to thinking: Why bother with putting the prism inside of the reservoir, when I could just as easily make it look like it was inside? The neat thing about bending light... is that it makes it really hard to tell what's going on behind the scenes. My ultimate goal was to fill the reservoir with light, so that it would illuminate the whole piece and allow me to display patterns and such. So... I simply laid the prism on top of the LED strip like so... 

And with the reservoir in front of it...

Not good enough yet. You can clearly see dots, which isn't what I want. I tried sanding the prism a bit more, to get a coarser grain on the faces:

Hey, not half bad! It's not glued in, mind you, so it's a little off kilter right now. That, and the effect isn't quite there yet.  It's too focused... too banded. I wanted a smooth effect. But how... 

I played with various combinations of frosted, white, and prism shaped pieces of acrylic to try and achieve the effect. Here's one with a translucent piece of white acrylic that is supposed to be good at dispersing light. Getting closer... but now it's pretty dim. The acrylic almost blocks too much light. 

After monkeying around, I got pretty close to what I wanted as far as appearance goes (again, it's not strait since the housing is in the way of the prism right now):

Almost a solid column of light! But... it takes quite a bit of material, and I'm not even sure it will fit in there correctly. I achieved this effect by putting the LED strip behind a 1" thick block of acrylic, and then putting a very thin strip of the diffusing acrylic on top, like so:

With this profile view, you can see why... see those angled beams of light coming out of each LED node? The dispersing white acrylic is far enough away from them (due to the 1" acrylic buffer) that those cones of light overlap. Now I just need to find a way to better disperse that light without requiring a full 1" gap. 

So today, I went and picked up a few more different shapes of acrylic... hopefully they arrive soon, so I can keep testing! I can feel the answer is close... I'm excited! 

Until next time!